Furnace for the thermic treatment of products supported by a gas cushion

ABSTRACT

Thermal treatment oven for products supported by a gas cushion, comprising a hearth provided with passages for the supporting gases, said hearth consisting of contiguous elements assembled longitudinally; the oven comprises, for example, a pushing device, giving the elements of the hearth a slow linear movement along its longitudinal axis.

United States Patent 8 1191 Moussou 1 1 May 28, 1974 1 FURNACE FOR THE THERMIC TREATMENT OF PRODUCTS SUPPORTED BY A GAS CUSHION [75] Inventor:

Jean Moussou, Pouzac, France Assignee: Ceraver, Paris, France Filed: Mar. 2, 1972 Appl. No.: 231,142

Foreign Application Priority Data Mar. 9, 1971 France 71.08072 US. Cl 432/258, 432/58, 432/122, 34/57 A Int. Cl. F27b 3/12, F27b 9/14 Field of Search 263/6, 28, 21 A; 214/1 BE; 432/58, 82,122, 155,11, 258; 34/31, 57 A; 248/363, 364

[56] References Cited UNITED STATES PATENTS 2,678,237 5/1954 Allander et al..... 214]] BE 3,325,157 6/1967 COOK 432/122 3,374,996 3/1968 Keough 432/122 3,375,094 3/1968 McMaster 214 1 BE 3,455,669 1 7/1969 McMaster ....'214 1 BE 3,455,671 7/1969 McMaster 214/1 BE Primary Examiner-John J. Camby Assistant Examiner-Henry C. Yuen Attorney, Agent, or Firm-Sughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT Thermal treatment oven for products supported by a gas cushion, comprising a hearth provided with passages for the supporting gases, said hearth consisting of contiguous elements assembled longitudinally; the oven comprises, for example, a pushing device, giving the elements of the hearth a slow linear movement along its longitudinal axis.

.3 Claims, 2 Drawing Figures BACKGROUND OF THE INVENTION supporting the products to be subjected to thermic treatment,.such as the firing of ceramic products,

passes.

This hearth is subjected to mechanical stresses due to its weight and to gas pressure, while it is brought to a high temperature, whereas its porous nature or the presence of holes reduces the mechanical strength thereof. The maintenance of the hearth, and its rapid repair therefore, constitute one of the greatest problems in this type of furnace.

The applicant has already proposed, in his-French Pat. application No. 7,102,205 of Jan. 22, 1971, to form the hearth of the furnace with separate elements which can be drawn from the assembly to avert accidents or to proceed with repairs. This still requires,

DESCRIPTION OF THE PREFERRED EMBODIMENT The furnace consists essentially of a channel which a hearth 2, consisting of contiguous elements 3, divides into two parts 4 and 5. The contiguous elements 3 are porous or drilled with holes 6 allowing the gases brought at 4 to a pressure greater than that which prevails at 5 to pass.

The heating and gas flow devices. which do not form a part of the invention, and are known per se, are not illustrated.

According to the invention, the drilled or porous hearth 2 crossed by a gas current which constitutes the gas cushion on which the products to be treated move, can move, for example, under the effect of a motordriven pusher 9 on the uprights 7 and 8. Devices such as the motor-driven pusher 9 are also known per se, but previously they have been used exclusively with supports for products to be fired in furnaces of a conventional type, without a gas cushion. The motor-driven pusher 9 is used to cyclically introduce into the furnace fresh elements 3A, while simultaneously pushing the previously introduced elements 3 towards the outlet end of the furnace.

however, the stopping of the furnace to remove the faulty element and replace it.

The invention proposes to give a simple solution for the problem of surveying the stateand rapid repairing of the hearth, not requiring the stopping of the furnace. Thus, it proposes to ensure continuous operation of such furnaces during very long periods. Lastly, it proposes to prolong-the operating period of the part of the hearth subjected to the severest thermo-mechanical Stresses.

SUMMARY OF THE INVENTION products to be subjected'to thermic treatment. This movement can be made in one direction or the other. The speed of movement-of the products subjected to the thermic treatment is independent from that of the hearth.

A furnace for firing ceramic products, according to the invention, is described hereafter, by way of an example, and with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 shows the entrance zone of the furnace in a longitudinal sectional view.

FIG. 2 shows it in a transversal sectional view.

The furnace thus produced enables not only surveying and easy maintenance of the hearth, but also improves the service conditions by limiting the exposure period of the elements forming the hearth in the high thermo-mechanical stress zone, for a same operating period.

Although the furnace described above constitutes the preferred form of embodiment of the invention, it will be understood that various modifications can be made thereto without going beyond the scope of the invention. More particularly, the form of the elements is not necessarily rectangular.

The elements need not occupy the whole width of the furnace, but only a fraction thereof, the furnace com prising, then, one or several low longitudinal walls intended for supporting the edges of the elements which do not rest on its lateral uprights. The holes 6 of the contiguous elements canbe oblique in relation to the longitudinal plane of symmetry of the furnace and/or in the direction of the progression of the products subjected to thermal treatment, so as to exert, on these, a centering and/or propelling effect.

What is claimed is:

l. A furnace for the continuous thermal treatment of products by supporting the products solely on gases over a hearth while heating the products and moving them through the furnace, said furnace comprising:-

a housing defining a channel;

a hearth enclosed within said housing and dividing said channel into an upper part and a lower part, said hearth comprising a plurality of contiguous elements placed side by side longitudinally in said channel and provided with passages for said gases;

means for providing said gases in said lower part of said channel under sufficient pressure so that, when said furnace is in use, said gases will pass through said passages in said hearth and support said products over said hearth while said products are heated and moved through said furnace;

means for moving said products through said furnace; and

4 said hearth.

3. A furnace as claimed in claim 1 wherein said means for moving said products through said furnace is adapted to move said products at a speed faster than the slow speed at which said mechanical means move the elements of said hearth through said furnace. 

1. A furnace for the continuous thermal treatment of products by supporting the products solely on gases over a hearth while heating the products and moving them through the furnace, said furnace comprising: a housing defining a channel; a hearth enclosed within said housing and dividing said channel into an upper part and a lower part, said hearth comprising a plurality of contiguous elements placed side by side longitudinally in said channel and provided with passages for said gases; means for providing said gases in said lower part of said channel under sufficient pressure so that, when said furnace is in use, said gases will pass through said passages in said hearth and support said products over said hearth while said products are heated and moved through said furnace; means for moving said products through said furnace; and mechanical means for giving the elements of said hearth a slow, unidirectional linear movement along a longitudinal axis of said channel, which unidirectional linear movement is independent of the movement of said products through said furnace.
 2. A furnace as claimed in claim 1 and further comprising a lateral upright extending vertically from the bottom of said channel and supporting a lateral edge of said hearth.
 3. A furnace as claimed in claim 1 wherein said means for moving said products through said furnace is adapted to move said products at a speed faster than the slow speed at which said mechanical means move the elements of said hearth through said furnace. 